1. Field of the Invention
This invention relates to applicators for glue or the like. In particular, this invention relates to a two piece applicator which is injection molded from resilient material and which is particularly suited for applying substances such as cyanoacrylate adhesive. Such applicators must be capable of accurately dispensing minute quantities of glue in precise locations. The applicator has a double wall construction with an air chamber between the walls. The double wall construction inhibits moisture and light from coming into contact with the adhesive. The air chamber assists in the dispensation of glue in a carefully metered drop-wise form which is easily controlled.
2. Description of Related Art
Prior art applicators for adhesives such as cyanoacrylate are subject to a number of problems. Such applicators are generally constructed of plastic material or thin metal such as aluminum in the form of tubes. Metal tubes are often cumbersome and it is difficult to control the drop-wise application of the glue. Plastic material is generally adversely affected by light and moisture and again many such applicators have difficulty in accurately and easily dispensing glue in a controlled manner.
The instant invention solves the above mentioned shortcomings of the prior art by providing an applicator constructed of resilient material wherein the sides of the applicator have a spaced apart double wall construction with an air chamber between the two walls. The double wall inhibits the amount of moisture and light which penetrates into the adhesive from the sides of the applicator. Also, the air chamber acts as a pneumatic cushion which enables fine control of the amount of glue dispensed. Spacers separate the inner and outer walls of the air chamber. The spacers are generally oriented vertically and placed in a location where the pinching action on the outer applicator body in dispensing adhesive by actuation between the thumb and forefinger places pressure on the spacer which in turn distributes the pressure over a large area of the inner container which holds the glue.
The applicator is preferably molded from resilient plastic material, e.g., resilient thermoplastic polymeric material such as high density polyethylene or polypropylene.
In a preferred embodiment, the applicator is molded in two parts. The applicator comprises an applicator body having a downwardly depending skirt with a shoulder adjacent its top, an applicator opening in the shoulder and a nozzle in fluid communication with the applicator opening. The applicator also comprises an inner container or cup which is fitted within the skirt of the applicator body with the cup opening in fluid communication with the applicator body opening. The inner side of the shoulder and the top of the inner side of the skirt have resilient locking means such as a resilient slot therebetween as well as peripheral beads and grooves for engaging cooperating resilient locking means at the top of the cup. The bottom of the cup and the skirt also have resilient locking means for holding the two parts together. There is general conformity in the shape of the walls of the cup with the opposed walls of the skirt along a major portion of the cup walls. The distance (space) between the walls of the skirt and the cup is substantially the same, in a horizontal plane, about the periphery of the cup walls and the skirt along a major portion of the cup walls. The skirt and cup are proportioned so that the inner sides of the skirt and the outer sides of the cup walls are separated by an air space and cooperative resilient locking means adjacent the top and bottom of the cup in cooperation with resilient locking means adjacent the top and bottom of the skirt form a fluid tight air chamber therebetween.
The cup also has at least one rib molded on its walls toward the skirt which extends from adjacent the bottom of the cup walls upwardly toward the top of the cup. The thickness of the rib acts as a separator to keep the sides of the skirt from contacting the sides of the cup walls. The sides of the applicator skirt are typically very smooth. To prevent slippage of the applicator, the outer side of the skirt has a friction area such as a series of raised elements which are in the general area opposite the cup rib. The raised elements on the outer surface of the skirt form a friction area over which the applicator is pinched or squeezed to cause pressure and inward flexing of the skirt. The flexing of the skirt transfers pressure to the spacer ribs of the cup and the air chamber which acts as a pneumatic cushion and which in turn cause an inward flexing action of the cup walls in order to dispense glue through the opening of the applicator body and through the elongated nozzle. The pneumatic cushion provides for better control in dispensing the glue in a metered and drop-wise manner.
The friction area on the outer side of the skirt will generally overlie the cup rib so that the pressure from the pinching or squeezing of the skirt is transferred to the cup by the rib. In a preferred embodiment, a vertical rib is on two of the opposite sides of the cup in substantial alignment with each other in a vertical plane. The skirt will also have friction areas on opposite sides of the skirt so that when the applicator is pinched in the friction areas the pressure is transferred to each of the cup ribs which act opposite to each other to transfer pressure and a flexing action to the cup.
By the term "resilient locking means" is meant locking or attaching means which depend on the resiliency of the members involved, e.g., wherein one member is forced within opposed walls of another to hold the members in place or wherein one member fits tightly about the inside or outside periphery of another. "Snap-locking means" are resilient detent means such as peripheral grooves and beads, portions of a groove or indentation or portions of a bead or raised surface which have resilient properties and permit the snapping in of a male part, e.g., a bead, with a female part, e.g., a groove, to hold two articles in place. It should be noted that only one member of the resilient locking means or the snap-locking means needs to be resilient. In addition to resilient locking means, other locking means can be used in this invention such as heat sealing or otherwise adhering the applicator body skirt adjacent to the bottom of the cup after the cup has been placed within the skirt.
The embodiments of the invention shown here are intended to enable the best mode of the invention that is known to the inventor. They should be taken as illustrative and not limiting and the scope of the invention should be limited only by the scope of the appended claims and their equivalents.